Engines produce power by combusting fuel and air in a combustion chamber to produce high-pressure combustion gases that drive a working member of the engine, such as a piston. Some of the combustion gases produced by an engine may be noxious. The combustion gases produced during operation of an engine may travel from the combustion chamber to the atmosphere, either through an exhaust system or through other portions of the engine, such as a crankcase.
At least one internal combustion engine has been conceived with provisions for recirculating at least a portion of the combustion gases produced by the engine back to the combustion chamber to reduce the quantity of noxious combustion gases emitted to the atmosphere. For example, U.S. Pat. No. 5,884,612 (“the '612 patent”) shows an engine with a blowby gas ventilation system for recirculating combustion gas from the crankcase to the combustion chambers of the engine. The engine includes a throttle body that channels air to a surge tank. The throttle body includes a butterfly valve that the air travels across as it flows to the surge tank. The engine also has a blowby gas ventilation pipe that directs combustion gases from the crankcase into the surge tank. The surge tank distributes the air and combustion gases to intake pipes, which channel the air and combustion gases to the combustion chambers of the engine.
Although the engine of the '612 patent recirculates combustion gases from the crankcase to the cylinders of the engine, the design includes disadvantages. For example, the butterfly valve in the throttle body presents a restriction to air flowing to the combustion chambers of the engine. This restriction may compromise the performance of the engine by reducing the airflow to the combustion chambers of the engine. The inclusion of the butterfly valve may also increase cost and maintenance requirements of the engine.
The combustion-gas recirculation system of the present disclosure solves one or more of the problems set forth above.